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ERRATUM NOTICE
General Certificate of EducationJanuary 2009Advanced Level Examination
CHEMISTRY CHM4
Unit 4 Further Physical and Organic Chemistry
Tuesday 20 January 2009 9.00 am to 10.30 am
Instructions to Invigilators
Before the start of the examination please ask candidates to amend their qu(Please read out this message twice to ensure understanding.)
Turn to Page 12, Question 5(c) (ii)
Cross out the number ‘4’ and insert the number ‘6’ in its place.
estion papers as follows.
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(JAN09CHM401)APW/Jan09/CHM4 CHM4
Surname
Centre Number
Candidate Signature
Candidate Number
Other Names For Examiner’s Use
General Certificate of EducationJanuary 2009Advanced Level Examination
CHEMISTRY CHM4Unit 4 Further Physical and Organic Chemistry
Tuesday 20 January 2009 9.00 am to 10.30 am
Time allowed: 1 hour 30 minutes
Instructions� Use black ink or black ball-point pen.� Fill in the boxes at the top of this page.� Answer all questions.� Answer the questions in Section A and Section B in the spaces
provided. Answers written in margins or blank pages will not bemarked.
� Show all your working.� Do all rough work in this book. Cross through any work you do not
want to be marked.� The Periodic Table/Data Sheet is provided on pages 3 and 4. Detach
this perforated sheet at the start of the examination.� Section B questions are provided on a perforated sheet. Detach this
sheet at the start of the examination.
Information� The maximum mark for this paper is 90.� The marks for questions are shown in brackets.� You are expected to use a calculator where appropriate.� Write your answers to the questions in Section B in continuous prose,
where appropriate. You will be assessed on your ability to use goodEnglish, to organise information clearly, and to use specialistvocabulary where appropriate.
Advice� You are advised to spend about 1 hour on Section A and about
30 minutes on Section B.
For this paper you must have� a calculator.
For Examiner’s Use
1
2
3
4
5
6
7
8
Question Mark Question Mark
Examiner’s Initials
TOTAL
Total (Column 2)
Total (Column 1)→
→
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APW/Jan09/CHM4
2 Areas outsidethe box will
not be scannedfor marking
1 In this question, give all values of pH to 2 decimal places.
1 (a) (i) Write an expression for pH.
...................................................................................................................................
1 (a) (ii) Calculate the pH of a 0.150 mol dm–3 solution of hydrochloric acid.
...................................................................................................................................
...................................................................................................................................(2 marks)
1 (b) A 60.0 cm3 sample of 0.0850 mol dm–3 aqueous potassium hydroxide was partiallyneutralised by the addition of 30.0 cm3 of 0.150 mol dm–3 hydrochloric acid.
1 (b) (i) Calculate the number of moles of potassium hydroxide used.
...................................................................................................................................
...................................................................................................................................
1 (b) (ii) Calculate the number of moles of hydrochloric acid added.
...................................................................................................................................
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1 (b) (iii) Calculate the number of moles of potassium hydroxide remaining in excess inthe solution formed and hence calculate the pH at 298 K of this solution.
Moles of KOH ...........................................................................................................
...................................................................................................................................
pH of solution formed ..............................................................................................
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...................................................................................................................................(7 marks)
SECTION A
Answer all questions in the spaces provided.
(02)
9
Page 4
3
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APW/Jan09/CHM4
1.0
HH
ydro
gen
1
4.0H
eH
eliu
m2
10.8B
Bor
on5
12.0C
Car
bon
6
14.0N
Nitr
ogen
7
16.0O
Oxy
gen
8
19.0
FF
luor
ine
9
20.2 N
eN
eon
10
27.0 A
lA
lum
iniu
m13
28.1 S
iS
ilico
n14
31.0
PP
hosp
horu
s15
32.1
SS
ulph
ur16
35.5 C
lC
hlor
ine
17
39.9 A
rA
rgon
18
6.9
Li
Lith
ium
3
6.9
Li
Lith
ium
3
9.0B
eB
eryl
lium
4
III
IIIIV
VV
IV
II0
*58
– 7
1La
ntha
nide
s
†90
– 1
03A
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ides
Key
rela
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atom
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ass
atom
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umbe
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le o
f th
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ents
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tom
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nd a
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show
n in
the
tab
le a
re f
or u
se in
the
exa
min
atio
n un
less
sta
ted
othe
rwis
e in
an
indi
vidu
al q
uest
ion.
23.0 N
aS
odiu
m11 39
.1K
Pot
assi
um19
40.1 C
aC
alci
um20
45.0 S
cS
cand
ium
21
47.9 T
iT
itani
um22
50.9
VV
anad
ium
23
52.0 C
rC
hrom
ium
24
54.9 M
nM
anga
nese
25
55.8 F
eIr
on26
58.9 C
oC
obal
t27
58.7 N
iN
icke
l28
63.5 C
uC
oppe
r29
65.4 Z
nZ
inc
30
69.7 G
aG
alliu
m31
72.6 G
eG
erm
aniu
m32
74.9 A
sA
rsen
ic33
79.0 S
eS
elen
ium
34
79.9 B
rB
rom
ine
35
83.8 K
rK
rypt
on36
85.5 R
bR
ubid
ium
37
87.6 S
rS
tron
tium
38
88.9
YY
ttriu
m39
91.2 Z
rZ
ircon
ium
40
92.9 N
bN
iobi
um41
95.9 M
oM
olyb
denu
m42
98.9 T
cTe
chne
tium
43
101.
1 Ru
Rut
heni
um44
102.
9 Rh
Rho
dium
45
106.
4 Pd
Pal
ladi
um46
107.
9 Ag
Silv
er47
112.
4 Cd
Cad
miu
m48
114.
8 InIn
dium
49
118.
7 Sn
Tin
50
121.
8 Sb
Ant
imon
y51
127.
6 TeTe
lluriu
m52
126.
9 IIo
dine
53
131.
3 Xe
Xen
on54
132.
9 Cs
Cae
sium
55
137.
3 Ba
Bar
ium
56
138.
9 La
Lant
hanu
m57
*
178.
5 Hf
Haf
nium
72
180.
9 TaTa
ntal
um73
183.
9 WTu
ngst
en74
186.
2 Re
Rhe
nium
75
190.
2 Os
Osm
ium
76
192.
2 IrIr
idiu
m77
195.
1 Pt
Pla
tinum
78
197.
0 Au
Gol
d79
200.
6 Hg
Mer
cury
80
204.
4 Tl
Tha
llium
81
207.
2 Pb
Lead
82
209.
0 Bi
Bis
mut
h83
210.
0 Po
Pol
oniu
m84
210.
0 At
Ast
atin
e85
222.
0 Rn
Rad
on86
223.
0 Fr
Fran
cium
87
226.
0 Ra
Rad
ium
88
227 A
cA
ctin
ium
89
†
140.
1 Ce
Cer
ium
58
140.
9 Pr
Pras
eody
miu
m59
144.
2 Nd
Neo
dym
ium
60
144.
9 Pm
Pro
met
hium
61
150.
4 Sm
Sam
ariu
m62
152.
0 Eu
Eur
opiu
m63
157.
3 Gd
Gad
olin
ium
64
158.
9 Tb
Terb
ium
65
162.
5 Dy
Dys
pros
ium
66
164.
9 Ho
Hol
miu
m67
167.
3 Er
Erb
ium
68
168.
9 Tm
Thu
lium
69
173.
0 Yb
Ytte
rbiu
m70
175.
0 Lu
Lute
tium
71
232.
0 Th
Tho
rium
90
231.
0 Pa
Pro
tact
iniu
m91
238.
0 UU
rani
um92
237.
0 Np
Nep
tuni
um93
239.
1 Pu
Plu
toni
um94
243.
1 Am
Am
eric
ium
95
247.
1 Cm
Cur
ium
96
247.
1 Bk
Ber
keliu
m97
252.
1 Cf
Cal
iforn
ium
98
(252
) Es
Ein
stei
nium
99
(257
) Fm
Fer
miu
m10
0
(258
) Md
Men
dele
vium
101
(259
) No
Nob
eliu
m10
2
(260
) Lr
Law
renc
ium
103
24.3 M
gM
agne
sium
12
(03)
Page 5
APW/Jan09/CHM4
4
Table 1Proton n.m.r. chemical shift data
Type of proton δ/ppm
RCH3 0.7–1.2
R2CH2 1.2–1.4
R3CH 1.4–1.6
RCOCH3 2.1–2.6
ROCH3 3.1–3.9
RCOOCH3 3.7–4.1
ROH 0.5–5.0
Table 2Infra-red absorption data
Bond Wavenumber/cm–1
C—H 2850–3300
C—C 750–1100
C C 1620–1680
C O 1680–1750
C—O 1000–1300
O—H (alcohols) 3230–3550
O—H (acids) 2500–3000
Gas constant R = 8.31 J K–1 mol–1
(04)
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2 In this question, give all values of pH to 2 decimal places.
2 (a) At 298 K, the pH of a 0.150 mol dm–3 solution of the weak acid HX is 3.48
2 (a) (i) Write an expression for the acid dissociation constant, Ka, for this acid.
...................................................................................................................................
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2 (a) (ii) Calculate the value of Ka for this acid, HX, at 298 K.
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...................................................................................................................................(4 marks)
2 (b) The value of the acid dissociation constant, Ka, for a different weak acid HY is2.65 × 10–4 mol dm–3 at 298 K.
Calculate the pH of the buffer solution formed when a 0.0300 mol sample of the solidsalt NaY is dissolved in 500 cm3 of a 0.250 mol dm–3 solution of the acid HY.
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(05)
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3 At a given temperature, in a closed container, a mixture of 0.360 mol of CO and 0.640 mol ofH2 was left to reach equilibrium according to the following equation.
CO(g) + 2H2(g) CH3OH(g) ∆H = –90.0 kJ mol–1
At equilibrium, 0.120 mol of CH3OH was present in the gaseous mixture.
3 (a) (i) Calculate the number of moles of CO and of H2 in this equilibrium mixture.
Moles of CO .............................................................................................................
Moles of H2 ...............................................................................................................
3 (a) (ii) Calculate the mole fraction of CO in the equilibrium mixture.
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................(4 marks)
3 (b) (i) Write a general expression to show how the partial pressure of a gas is related toits mole fraction.
...................................................................................................................................
3 (b) (ii) The total pressure of the gases in the equilibrium mixture formed in part (a) was268 kPa. Calculate the partial pressure of CO in this mixture.
...................................................................................................................................
...................................................................................................................................(2 marks)
3 (c) A different equilibrium mixture of CO, H2 and CH3OH was prepared at a giventemperature and a total pressure of 500 kPa. In this mixture, the partial pressure of COwas 75.0 kPa and the partial pressure of H2 was 300 kPa.
3 (c) (i) Calculate the partial pressure of CH3OH in this mixture.
...................................................................................................................................
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(06)
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3 (c) (ii) Write an expression for the equilibrium constant, Kp, for this reaction.
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3 (c) (iii) Calculate a value for the equilibrium constant, Kp, at this temperature and give itsunits.
Calculation ...............................................................................................................
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Units .........................................................................................................................(5 marks)
3 (d) (i) State the effect, if any, at a constant temperature of an increase in total pressureon the mole fraction of CH3OH and on the value of the equilibrium constant Kp.
Effect on mole fraction of CH3OH ...........................................................................
Effect on Kp ..............................................................................................................
3 (d) (ii) State the effect, if any, at a constant pressure of an increase in temperature on themole fraction of CH3OH and on the value of the equilibrium constant Kp.
Effect on mole fraction of CH3OH ...........................................................................
Effect on Kp ..............................................................................................................(4 marks)
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(07)
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4 Compound B exists as a pair of stereoisomers which can be formed from compound A.
4 (a) Name compound A.
.............................................................................................................................................(1 mark)
4 (b) (i) Give the reagent and conditions used to convert A into B and name the type ofreaction involved.
Reagent .....................................................................................................................
Conditions ................................................................................................................
Type of reaction ........................................................................................................
4 (b) (ii) Draw the structural isomer of B which is also formed from A under the sameconditions.
(4 marks)
4 (c) (i) Name the type of stereoisomerism shown by B.
...................................................................................................................................
4 (c) (ii) Explain why this type of stereoisomerism is possible in B.
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................(3 marks)
(08)
C
A B
CH3
CH2
CH3
Br
CH2CH3 C C
H3C H
CH3CH2 CH3
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4 (d) (i) Suggest why the mass spectrum of A (C6H13Br) contains two molecular ionpeaks of almost equal intensity at m/z = 164 and m/z = 166
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4 (d) (ii) There is a major peak at m/z = 85 in the mass spectrum of A. Draw the structureof the species which gives rise to this peak. Give one reason why this peak is amajor one.
Structure
Reason ......................................................................................................................
...................................................................................................................................(4 marks)
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(09)
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5 The infra-red spectra shown below are those of compound C and of compound D.
In the laboratory, a student converted C (C6H14O) into D (C6H12O) by heating C withacidified potassium dichromate(VI).
5 (a) (i) Identify the bonds responsible for the absorptions labelled I and II in theinfra-red spectra above.
I ................................................................................................................................
II ...............................................................................................................................
5 (a) (ii) The absorption labelled III is due to an impurity present in the sample of Dmade by the student. Suggest one possible impurity which would produce thisabsorption.
...................................................................................................................................(3 marks)
(10)
4000 3000 2000 1500 1000 500Wavenumber / cm–1
100
Transmittance / %
Compound C
Compound D
50
III
II
I0
4000 3000 2000 1500 1000 500Wavenumber / cm–1
100
Transmittance / % 50
0
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5 (b) The proton n.m.r. spectrum of C (C6H14O) shows 4 peaks.
The table below gives the chemical shifts, δ values, for each of these peaks, togetherwith their splitting patterns and integration values.
State what can be deduced about the structure of C from the presence of the followingin its proton n.m.r. spectrum.
5 (b) (i) The singlet peak at δ = 0.89
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5 (b) (ii) The two peaks at δ = 3.47 and δ = 1.12
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5 (b) (iii) Use the information in part (a) and part (b) to deduce the structure of C.
(4 marks)
Question 5 continues on the next page
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δ / ppm 3.47 1.63 1.12 0.89
Splitting pattern quartet singlet doublet singlet
Integration value 1 1 3 9
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5 (c) Draw the structures of the alcohols described below which are isomers of C (C6H14O):
5 (c) (i) a compound which is unaffected by acidified potassium dichromate(VI) and has4 peaks in its proton n.m.r. spectrum,
5 (c) (ii) a compound which exists as optical isomers and has 4 peaks in its proton n.m.r.spectrum.
(2 marks)
5 (d) Draw the structure of an alcohol which is an isomer of D (C6H12O) but which has noabsorption between 1620 and 1680 cm–1 in its infra-red spectrum.
(1 mark)
10
(12)
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(13)
6 (a) (i) The rate equation for the reaction between compounds E and F at a giventemperature is
rate = k[E][F]2
The initial rate of reaction is 9.45 × 10–4 mol dm–3 s–1 when the initial concentrationof E is 0.76 mol dm–3 and the initial concentration of F is 1.22 mol dm–3. Calculatea value for the rate constant, k, at this temperature and state its units.
Value of k ..................................................................................................................
...................................................................................................................................
...................................................................................................................................
Units of k ..................................................................................................................
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6 (a) (ii) Calculate the initial rate of reaction when the concentration of E is doubled and atthe same time the concentration of F is halved but the temperature is not changed.
...................................................................................................................................
...................................................................................................................................(4 marks)
6 (b) The following data were obtained by studying the reaction between compounds G andH at a constant temperature.
6 (b) (i) Deduce the order of reaction with respect to G.
...................................................................................................................................
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6 (b) (ii) Deduce the order of reaction with respect to H.
...................................................................................................................................
...................................................................................................................................(2 marks)
Initial InitialInitial rate /Experiment concentration concentrationmol dm–3 s–1
of G / mol dm–3 of H / mol dm–3
1 0.20 0.25 6.80 × 10–3
2 0.30 0.25 15.3 × 10–3
3 0.60 0.50 61.2 × 10–3
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(15)
7 Consider the reaction sequence shown below.
7 (a) Compound J is produced by the reaction of methylbenzene with the NO2+ ion. This
ion is formed by the reaction of concentrated nitric acid with concentrated sulphuricacid.
State the role of concentrated nitric acid in its reaction with concentrated sulphuricacid.
Name and outline a mechanism for the reaction of methylbenzene with the NO2+ ion.
(5 marks)
7 (b) Name the type of reaction involved in the conversion of J into K (Reaction 2).
Draw the structure of the compound formed when compound K reacts with methanolin the presence of a small amount of concentrated sulphuric acid.
(2 marks)
7 (c) Compound L is prepared by the reduction of K in Reaction 3.
Give reagents and write an equation for Reaction 3. Use [H] to represent the reducingagent.
(2 marks)
7 (d) In the presence of a catalyst, L can polymerise.
Name the type of polymerisation which occurs. Draw the repeating unit of thepolymer and name the type of linkage involved.
(3 marks)
SECTION B
Detach this perforated sheet.Answer both questions 7 and 8 in the spaces provided on page 14 and pages 17–20.
Reaction 1 Reaction 2 Reaction 3
CH3 CH3
NO2
COOH
NO2 NH2
COOH
J K L
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(16)
CCH3CH2 CH3
O–
X
CN
CCH3CH2 Cl
O–
Y
N+H H
H
8 The intermediates, X and Y, shown below are formed by nucleophilic attack on two differentcompounds containing a carbonyl group.
8 (a) Outline a mechanism for the complete reaction in which X is an intermediate.Name the final product formed from X.
(5 marks)
8 (b) Outline a mechanism for the complete reaction in which Y is an intermediate.Name this mechanism and name the final organic product formed from Y.
(6 marks)
8 (c) Species Z is shown below.
Name the type of species of which Z is an example and draw the product formed whenZ reacts with an excess of aqueous sodium hydroxide.
(2 marks)
8 (d) Aspirin is an ester prepared industrially by the reaction of ethanoic anhydride with2-hydroxybenzenecarboxylic acid shown below.
Write an equation for this reaction showing clearly the structure of aspirin.Give two reasons why ethanoyl chloride is not used in this industrial preparation.
(5 marks)
END OF QUESTIONS18
CCH3CH2 H
COO–
Z
N+H H
H
COOH
OH
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